In my prior U.S. Pat. No. 5,251,569, dated Oct. 12, 1993, the details of which are herein incorporated by reference, there is disclosed a multiple tone whistle. A whistle resonating chamber is in fluid communication with the mouth piece and has an opening to the exterior of the whistle body. Knock outs are provided in the whistle body and extend to the resonating chamber. When a knock out is removed, it creates a pitch altering opening to the resonating chamber. The greater the desired variation from the original tone, the greater the number of knock outs that are removed.
Such a whistle works extremely well for its intended purpose, particularly when employed in the environment a whistle having two distinct resonating chambers. By altering the tone of one resonating chamber with respect to the other, the resulting sound may be made to range from an extremely strident tone to a tone of two pitches essentially in harmony with one another.
However, once the whistle tone is selected by removing one or more of the knock outs, it is not particularly practical to return to or towards the original tone. Of course, one could use an object such as a piece of tape to cover one of the opened tone altering openings whose knock out has been removed, but that is not the most practical in that such a piece of tape can easily become disassociated from the whistle or become punctured. In such a case, the original tone of the whistle cannot be maintained.
The present invention is directed to overcoming one or more of the above problems.